Differential pressure cleaning apparatus



March 3, 1959 E. H. YON'KERS A 2,875,846

' DIFFERENTIAL PRESSURE CLEANING APPARATUS Filed April 4, 1955 1 v 3Sheets-Sheet 1 IN V EN TOR.

Edgy/2d E. H. YONKERS DIFFERENTIAL PRESSURE CLEANING APPARATUS March 3,1959 5 Sheets- Sheet 2 Filed A; ril 4, 1955 O jVENTOR;

[Ma J17 \N a I mmww 7 4 March 3, 1959 E. H. YONKERS 2,375,346

DIFFERENTIAL PRESSURE CLEANING APPARATUS 3 Sheets-Sheet 3 Filed April 4,1955 "iifi i 442 V 1 INVENTOR. W N ;l 1--- [may 1504 15? J65 BYDIFFERENTIAL PRESSURE CLEANING AP ARATUS The present invention relatesgenerally to differential pressure cleaning apparatus and moreparticularly to a combined suction-pressure type cleaning device of thetype employing a circulating air stream under pressure to dislodge dustparticles from an area to be cleaned and also employing the suctioncreated by the pressure source for returning the dust laden air streamfor filter- While the apparatus of the present invention is capable ofperforming a wide variety of functions, it is particularly well suitedfor utilization in the graphic arts industry and, accordingly, theensuing description is directed primarily to its use in this particularcontext. In the graphic arts industry, the sheet poper receiving theprinted material frequently contains a number of impurities in the formof relatively losse particles such as protruding fibers and the likewhich, unless removed from the sheet, generally tend to collect upon andadhere to the printing type, thereby to cause smearing or distortion ofthe printed image. Moreover, and even more important, it is commonpractice in this industry to print upon one side of a sheet and then tosprinkle or dust powdered material such as cornstarch over the surfaceof the sheet prior to a second printing operation on the reverse side.The above described dusting operation avoids difiiculties in thehandling and storage of the sheet after the first printing operationwhich would otherwise be encountered as a result of the thickness of theprinted material on only one side of the sheet, these difficulties beingcommonly referred to in the art as offset problems. However, it isimperative that the powdered material be romoved from the sheet prior tothe second printing operation in order to avoid the difficultiesmentioned above with respect to the collection of loose material uponthe printing type. Accordingly, one of the principal objects of thepresent invention is to provide an improved cleaning apparatus of thechar.- acter described above wherein the aforementioned dimculties areobviated.

Another object of the present invention is to provide a new and improveddifferential pressure cleaning apparatus which is characterized bysimple, inexpensive construction but is adapted to provide continuousfaultfree operation over an extensive period of time.

A further object of the invention is to provide a new and improvedclosed differential pressure cleaning system for circulating air underpressure to a given area in order to dislodge and stir up dust particlesin that area and for withdrawing the dust laden air for filtering andrecirculation.

It is also an object of the present in vention to provide a cleaningsystem of the type described above wherein the circulated air isconstantly employed to clean the filtering device thereby to provide anextremely long lived continuously operating system wherein the necessityfor frequent replacement of the components of the apparatus, such as thefilter, is avoided.

[It is likewise an object of the present invention to pros Patentice 2vide a cleaning system of the character described i l: eluding acontinuously moving filter for separating the dust from the circulatingair stream wherein the incorn: ing air is directed across the filtersurface in order to dislodge particles collected thereon, thereby toclean the filter and establish equilibrium operating conditions for thesystem. i

The foregoing and other objects are realized, in ac cordance with thepresent invention, by providing a l s typ ning sys em n lud ng a cl an nhead f r gath ng u l ,den air from n a e to be clean d- The cleaninghead is placed in fluid eornmunic with a combined pressure-suctionsource which rec ,s th d st a n a fi ters it, and e r s subs a ial ydust free air under pressure to the cleaning head in order to agitateand loosen the dust particles in the area to be cleaned. The filteringequipment comprises a moving type filter interposed in the path oftravel of the dust laden air stream for the purpose of collecting dustand passing relatively clean air to the pressure-suction source forrecirculation. In order to remove the particles C0 lected upon themoving filter at least a portion of the incoming air is directed acrossthe filter surface thereby cleaning the filter and depositing thedislodged particles in a suitable collecting chamber for removal. Thus,the circulating air establishes equilibrium operating conditions for theclosed sy tem and provides for continuous operation without replacementof the filter or other com; ponent elements of the apparatus.

The invention both as to its organization and method of operation,together with further objects and advan: tages thereof, will best beunderstood by reference to, the following detailed description taken inconjunction. with the accompanying drawings wherein:

Fig. 1 is a broken away plan view showing the clean,- ing head and theducts leading thereto of the apparatus of the present inventionassembled upon a typical print? ing press;

Fig. 2 is an enlarged partial sectional view taken along a linesubstantially corresponding to the line 2.2 in Fig. 1 and illustratingthe cleaning head positioned to remove dust and other loose particlesfrom a traveling sheet of paper;

Fig. 3 is an enlarged broken away bottom view of a portion of thecleaning head of the present invention as viewed when looking in thedirection of the arrows 31-3 in Fig. 2;

Fig. 4 is an enlarged broken away sectional view of a portion of thecleaning head illustrated in Figs. 1 to 3r inclusive, and shows theeffect of the cleaning head upon.

the traveling paper sheet;

Fig. 5 is a front elevation view partially in section of apparatuscharacterized by the features of the present in: vention with certain ofthe component elements being broken away in order to facilitate theillustration;

Fig. 6 is a side elevation view partially in section of the apparatusshown in Fig. 5 with a major portion of the side panel of the housingand a considerable portion of the filter drum being broken away;

F 7 is a s t ona iew in le n o a a t rnat e r an e en o the appa f hPres nt in nt on;

Fig. 8 is a plan view partially in section of the ap paratus shown inFig. 7 with the top of the housing re.-

moved to enhance the illustration; and

Fig. 9 of the apparatus shown in Fig. 7 particularly illustrating thevibrating mechanism for removing dust from the filter.

Referring now to the drawings and more particularly to Figs. 1 to 4thereof, a cleaning head 10is there illustrated for removing dust andother loose particles.

from an area to be clea ed and compr ing an el n is an enlargedfragmentary view of a portion gated substantially rectangular housingdivided into a pressure compartment 10a {and a suction compartment 10bby a partition 10c extending longitudinally of the housing.

As previously indicated, the apparatus of the present invention isparticularly well suited for operation in conjunction with machineryconventionally employed in the graphicarts industry. Thus, asillustrated in Fig. 2, the cleaning head 10 is adapted to remove dustand other .loose particles from a traveling sheet of paper 15 carriedupon a feed roller 16 of a printing press which maybe of anyconventional type. Since the printing press per se forms no part of thepresent invention only certain representative portions of a few of theelements thereof associated with the apparatus of the present inventionhave been shown in Figs. 1 and 2. Thus, the

- sheet feeding roller 16 is illustrated as a broken away portion of acylinder rotatably supported upon suitable supporting structureindicated generally by the reference numeral 17. For the purpose ofcooperating with the feed roller 16 to move the sheet of paper 15, thereis provided a feed cylinder 19 having its periphery in engagement withthe outer surface of the paper. The traveling paper sheet 15 is passedby the pair of feed rollers beneath a printing cylinder 20 which, ofcourse,

carries printing type (not shown in the drawings) upon its outer face inorder to impress the desired image upon the sheet. The printing cylinder20 is rotatably supported upon a mounting means 21 in spaced parallelposition with respect to the feed cylinder 19 and in juxtaposition tothe supply roll 16.

As previously mentioned, the paper sheet is conventionally sprinkledwith powdered material such as cornstarch after the printing'cylinder 20has applied an image to one side ofthe paper and prior to printingon thereverse side. It is a primary purpose of the apparatus of the presentinvention including the cleaning head 10 to remove this powderedmaterial and other loose particles appearing on the sheet 15 prior toengagement of the sheet by the printing cylinder 20 for the second printing operation on the reverse side of the sheet.- As described above,dust or other particles present on the sheet, unless removed, tends tocollect upon the type carried on the printed cylinder and causes theaforementioned difiiculties with respect to distortion and smearing ofthe printing image.

Printing presses are generally designed for an optimum use of space,and, as a consequence, the spacing usually provided between the feedcylinder 19 and the printing cylinder 20 is somewhatlimited.Accordingly, the cleaning head 10 and its associated elements must bedesigned to be accommodated within this limited space withoutinterfering with the operation of the other moving parts of the press.To this end, the cleaning head 10 is illustrated in Fig. 2 as beingassembled upon an elongated rod or bar 11 extending between fixedparallel frame members 12 of the printing press. For the purpose ofsupporting the bar 11, the opposed ends thereof carry mounting supports13 which are bolted or otherwise secured to the frame members asindicated by the machine screws 14 shown in Figs. 1 and 2.

In order to provide for adjustment of the position of the cleaning head10 upon the press, thereby to facilitate operation with different typepresses or with presses employing feed rollers 16 having differentdiameters, the bar 11 carries a plurality of spaced adjustablesupporting ,means 22. Each of these supporting means comprises a member23 bifurcated at one end in order to straddle 3. lug 24 carried by thecleaning head 10 and provided at its other end with an internallythreaded bore 23a for receiving an adjusting screw 26. The bifurcatedend of the member 23 is attached to the lug 24 in any suitable manner asby the nut and bolt assembly 25. The adjusting screw 26 is retainedwithin the bore 23d by means of-a nut 26a in engagement with the endportion of the member 23. The adjusting screw 26 of each of thesupporting means 22 is also accommodated within an internally threadedbore 27a of a support 27 carried by the bar 11 and is retained thereinby means of a nut 26b engaging the end portion of the support. Thus, itwill be observed that limited adjustment of the position of the cleaninghead 10 toward andaway from the feed roller 16 for the purpose discussedabove, may be efiected by loosening nuts 26a and 26b and turning theadjusting screw 26. Since the bar 11 is oriented in fixed position uponthe press, rotation of lead screw 26 induces movement of the cleaninghead 10 toward or away from the bar, the direction of this movement, ofcourse, being a function of the direction of rotation of the adjustingscrew. When the cleaning head has been moved to the desired positionwith respect to feed roller 16, the nuts 26a and 26b are tightened inorder to provide a rigid supporting assembly for maintaining thecleaning head in fixed position in proximity to the traveling sheet ofpaper 15. Thus, by proper adjustment of the screw 26, the cleaningapparatus of the present invention may be rendered effective foroperation with printing presses of different design or with printingpresses employing feed rollers 16 of different diameter.

For the purpose of supplying relatively clean air under pressure to thehead 10 from a combined pressure-suction source of the type shown eitherin Figs. 5 and 6 or in Figs. 7 and 8 to be described in detailhereinafter, there is provided a duct or flexible tubing 29 which isconnected at one end to the outlet of the source and at the other end toa manifold 30. A similar duct or tubing 31 is connected between theinlet to the source and a manifold 32 in order to withdraw dust, ladenair from the head 10. The manifolds 30 and 32 are supported in spacedparallel positions by a plurality of suitable brackets 33 carried uponthe bar 11 and are respectively connected to the pressure compartment10a, and to the suction compartment 10b by a plurality of ducts orflexible tubes 34 and 35. The relatively clean indicated, functions toagitate the dust or loose particles collected on the surface of thepaper sheet 15 and creates a dust laden air volume which is drawn intothe suction compartment 10b through an elongated slot 10 ina secondslanted bottom portion 10g of the cleaning head 10. Since the cleaninghead is located in proximity to the traveling paper sheet, the suctionin compartment 10b draws the paper into the cavity formed by the slantedbottom portions 10c and 10g as shown in Fig. 4, thereby to create asmall substantially enclosed space 36 containing dust laden air forwithdrawal through the suction compartment 10b, through ducts 35 andinto manifold 32. Movement of the paper sheet 15 into the space 36straightens the traveling sheet andholds it in proper position forregistry with the printing type carried upon the cylinder 20. The flowof relatively clean air from the compartment 10a and.into, the space 36is indicated by the arrow pointed line 37 in Fig. 4, while the flow ofdust laden air from space 36 into suction compartment 10b is indicatedby arrow pointed line Turning now to Figs. 5 and 6 for a description ofthe combined pressure-suction source for delivering the dustj thecleaning head 10 and for withdrawing the dust laden air from.

free air to the pressure compartment 10a of compartment 10b forfiltering and recirculation, the

equipment there illustrated comprises an enclosed re'ctangularly shapedhousing 40 supported upon casters or wheels 41 to'facilitate itsmovement to any desired location. The duct 31 connected to suctionmanifold 32 near the printingpress functions to deliver dust laden airthrough the inlet 39 to an inlet chamber 42 formed between the Walls ofhousing 40 and a drum 43 rotatably supported therein. The drumpreferably comprises a perforated metal sheet covered by a relativelycoarse porous fabric material and including an outer lamination of veryfine porous filter preferably with a smooth outer surface which may be atextile or paper. The graded porosity of the filter permits maximumeffectiveness of the fine filter since, if the latter were placedcontiguous to the perforated metal sheet, it would be effective only inthe areas over the perforations and would be sealed against theunperforated metal between the holes. The outer surface of the finefilter is preferably smooth in order to enhance the self cleaning of thefilter as described in detail hereinafter. mits all of the fine filterpores to operate by providing leakage paths to the holes in the metal,thereby forming passageways for air flowing from the inlet chamber 42into a suction chamber 44 enclosed by the drum '43.. A fan driveassembly, indicated generally by the reference numeral 45, is disposedwithin the suction chamber. 44 for the purpose of rotating a fan 46. Thedrum 43 also encloses a drum rotating mechanism indicated generally as47. The fan drive assembly 45 includes a rigid motor support bracket,comprising a plurality of spaced, parallel braces 48 rigidly supportedat one end upon one wall of the housing 40 and having an end plate 49bolted or otherwise secured to their other ends. A fan driving motorStl, preferably of the electrically operated type having a speed of 3600revolutions per minute is-mounted upon the motor supportbracket as bythe nut and bolt assemblies 43a shown in Fig. 6.

The drum rotating mechanism 47 preferably includes a small electricmotor 51 supported upon the end plate 49 in any suitable manner as byspaced bolts 52 interconnecting the end plate 49and a bracket 53 on themotor, The motor 51 is adapted to drive its shaft 54 at any suitable butrelatively low speed. A small spur gear 55 carried by motor shaft 54cooperates with a large gear 56 to form a speed reduction drive forshaft 57 having one end rotatably journalled within .a hearing assemblymounted upon the end plate 49 and having a drum support plate 5 securedto its other end. in order to impart the rotation of the shaft 57 todrum 423, the latter attached as by machine, screws 60 to the drumsupporting plate '59.

The speed of, rotation of the drum =53 is a function of the speed ofrotation of motor 51 and also of the peed reduction effected by thegears 55 and '56 and, in one particular application of the apparatus ofthe pnesent invention a rate of rotation of the drum of about one-sixthrevolution per minute was found to produce satisfactory results.

,In order to provide access to the interior of. the housing 4-0 forrepair or service of the apparatus embodied therein, one of its sidepanels 46a is preferably removable. To facilitate removal of this panel,there is provided a handle 6?. which may be raised until the lower endof the panel tit e is lifted above the level of lip ltlb .at which timethe panel may be withdrawn. \ltlith the panel 4% removed the drum 43,may be disassembled zfrom its drive mechanism 47 by loosening a setscrew 81a holding a drum retainer ring 81 upon the shaft 57. After setscrew 81a is loosened the ring Sl may be removed and the drum 43 may belifted from the housing to permit access '.to the component elements ofthe fan drive assembly 4-5 and of the drum rotating assembly 47. Afterthe necessary repairs and service have been completed, the equipmentmay, of course, be re-assemblied by inserting the removed parts in theproper positions.

"In order to supply electrical energy for actuating both of the motors50 and 51, an electrical connection box The coarse fabric per 61 issupported externally of the housing 40 upon one of its end walls;' Theinlet to the connection box 61' comprises a suitable electricalconductor 63 having one end terminating in a conventional plug 64adapted to be connected to a suitable source of power not shown in thedrawings. With the plug 64 connected to the source of power and with astart-stop switch 65 in the connection box 61 in the on position,indicating light 66 is illuminated and energizing current issimultaneously' applied to the motors 50 and 51 with the result that thedrum 43 is continuously rotated at relatively low speed preferably inthe direction of the arrow 43a in Fig. 5, while, at the same time, the.fan 46 is rotated at high speed. In order to prevent the entry of dustladen air directly from the inlet chamber 42 into the suction chamber 44without passing through the filter on the drum 43, the drum carries anannular resilient, disc 67 having a curved end portion 67a in continuousengagement with an annular ring 68 mounted internally of the housing llon one of its walls. The ring 68 is preferably formed of a layer ofsponge rubber and I high speed by the motor a relatively thin. feltlamination and, accordingly, provides an air sealed cushion for the endportion 67a.

The fan 46 may be of any suitable construction but preferably comprisesa pair of parallel discs 46a and 46b supporting a plurality of spacedradial vanes 46c and carried upon shaft Ella driven by the motor Thedisc 46a is attached to the shaft 59:: by means of a mounting assemblyincluding a plate 5% bolted or otherwise secured to that disc. When thefan 4.6 is rotated at 59, a suction is created within the chamber 44enclosed by drum 43 in order to draw dust laden air through the filtercarried by the drum, The dust is collected by the filter so that the airpassing into the suction chamber 44; is relatively clean. This clean airis passed through the fan 46 in order to create a pressure within apressure chamber 69 formed by a panel memberdfic of the housing 46. Inorder to minimize the direct flow of air between the pressure chamber 69and the suction chamber 44 around the face of the fan 46 there isprovided an annular ring 70, similar in construction to the ring 68,located in proximity to the fan 46 and carried upon a wall 40:! of thehousing 40. The air within the pressure chamber 69 is delivered from anoutlet 71 through the duct 29 to the cleaning head it).

In order to provide for constant removal of the dust collected by thefilter, thereby to effect continuous opera-- tion of the equipment, thedust laden air flowing through inlet 3% is directed by a suitable baffle39a across the surface of the filter on the drum 43. It will be observedthat the outer periphery of the drum 43 is relatively close to the wallsof the housing 40 at certain points in the inlet chamber designated bythe reference numerals 42a and 62b. At these particular points the dustladen air in the inlet chamber 42 is acceleratedwith the result that airflows across the filter with sufiicient force to dislodge the dust andother particles accumulated thereon. The bafile 39a reduces turbulencein the inlet chamber 42 and, in effect, assures travel of the air acrossthe surface of the drum in a single direction as indicated by the arrowpointed lines 42c in Fig. 5. The dust removed from the filter fallsthrough the inlet chamber to the bottom of the housing where it isdeposited within a suitable drawer 72 having a handle 72a thereon topermit removal of 1 the dust while the apparatus is in operation. Aplurality of vertical bafiles 72b in the drawer 72 reduce turbulence ofthe air flowing Within the inlet chamber 42 and induce an approximatelyuniform distribution of dust particles Within the various drawercompartments formed by these- 3 bafiles, i

under approximately uniform operating conditions. Since under continueduse of the equipment.

presses since the dust removed from the filter accumulated Within drawer72 may be removed without shutting down either the press or the cleaningapparatus. Furthermore, since the filter is continuously cleaned by airfrom the inlet 39, it will possess an extremely long useful life withoutrequiring replacement.

From the foregoing explanation, it will be apparent that when theapparatus shownin Figs. 1 to 6, inclusive, is placed in operation byactuating the starting switch 65, the motors 50 and 51 are energized inorder to rotate the drum 43 and to drive the fan 46. Rotation of the fancreates pressure within the pressure chamber .69 to induce a flow ofrelatively clean air from the outlet 71, through duct 29, into manifold30, through ducts 34, into pressure compartment 10a in the cleaning head10 and through the slot 10d. The air emerging from slot 10d impingesupon the traveling paper sheet, removes the dust and other looseparticles collected thereon and produces a dust laden air stream withthe space 36. The suction created by rotation of fan 46 withdraws thedust laden air from space 36 through slot 10 into suction compartment10b, through ducts 35, into suction manifold 32, through duct 31,through the inlet 39, and into the inlet chamber 42 within the housing.The dust in the air supply within chamber 42 is removed by the filtercarried upon drum 43 as the air is drawn into the suction chamber 44 forrecirculation by the fan 46. Dust particles collected on the surface ofthe filter are dislodged by acceleration of the air flowing through theinlet 39 at the points 42a and 42b of the inlet chamber, thereby todeposit the dust particles in the drawer 72 at the bottom of the housing40 for removal. Thus, it will be observed that the apparatus describedcomprises a closed system wherein the circulated air not only stirs upand removes dust from an area to be cleaned but also functionscontinuously to clean the filtering equipment for removing dust from thecirculated air stream.

Turning now to Figs. 7 and 8 for a description of an alternativearrangement of the combined pressure-suction source adapted to operatein conjunction with the cleaning equipment shown in Figs. 1 to 4,inclusive, apparatus is there illustrated comprising a housing 140having an inlet 139 connected through duct 31 to the manifold 32.Structure, including a pair of plates 141a and 141b, is provided withinthe housing in order to form an inlet chamber 142 for receiving dustladen air from the inlet 139. The plate 141a is perforated to permit thepassage of airfrom the inlet chamber 142 as indicated by the arrowpointed lines passing through this plate. A chamber forming housing 148cooperates with the plate 141a to define a suction chamber 144 and alsocooperates with the plates 141a and 141b to define a pressure chamber169. An endless belt 143 of suitable filter material such as porousfilter paper surrounds the plates 141a and 141b and is continuouslymoved thereover in the direction indicated by arrow pointed line 143a bymeans of a filter drive assembly indicated generally by the referencechar acter 147. This drive assembly comprises a small electric motor'151mounted upon one of the walls of the housing 140 and adapted to drive afriction type belt driving roller 152' through a speed reductionmechanism 153 including worm gear 154 and driven gear 155. An idlerassembly 156 mounted for pivotal movement about a pin 157 secured nearthe top of the housing 140 functions to maintain proper tension on theendless belt 153. The latter idler assembly comprises an arm 158 whichsupports a 8. with the belt and a spring 160 which normally urges-thebracket 158a and roller 159 toward the pivot pin 157'in order to tensionthe belt.

In order to create pressure within the pressure chamber 169 and, at thesame time, to produce suction within the chamber 144, there is provideda fan 146 driven at relatively high speed in the direction indicated byarrow pointed line 166 in Fig. 7 by a fan drive assembly indicatedgenerally as 145. The fan drive assembly comprises an electric motormounted upon a motor support 149 which is attached to the plate 141a inany suitable manner as by the machine screws 149a shown in Fig. 7. Themotor 150 rotates its armature shaft 150a and a pulley 161 mountedthereon in order to drive a belt 162 and impart the rotation of thearmature shaft to a fan drive shaft 164 through a pulley 163. The fandrive shaft 164 is journalled within a suitable bearing assembly asindicated at 165. and extends from this bear! ing assembly throughpressure chamber 169, through opposed parallel walls of the chamberforming housing 148, and through the suction chamber 144 to receive thefan 146. The latter fan comprises a pair of parallel discs 146a and 146binterconnected by a plurality of spaced, curved vanes 146s and functionsto create pressure within the chamber 169 for delivering relativelyclean air from outlet 171 of the housing through duct 29 to the cleaninghead 10.

The chamber 144 is open to the suction side of the fan 146 so that thepressure within this chamber is less than that of the inlet chamber 142.The suction withinthe chamber 144 created by rotation of the fan 146draws air from the inlet chamber 142 through the endless filter 143 andthrough the perforations in plate 141a in order to separate the dustparticles from the air. The separated particles, of course, tend toaccumulate upon the filter 143 but are removed to some extent by astream of. dust laden air directed from the inlet 139 across the surfaceof the filter by means of a battle 139a. The latter battle is preferablylocated in proximity to the moving filter belt 143 and, hence, prohibitsthe passage of dust laden air directly to the outlet 171 Without passingthrough the filter. Particles dislodged from the filter 143 by the airstream are passed directly to the bottom of the housing 140 as indicatedby the arrow pointed lines 167 in Fig. 7 where they are collected withina drawer 172. In order to provide for withdrawal of the drawer andremoval of the dust collected therein without terminating the operationof the cleaning apparatus, the drawer is provided with a handle 172a.

For the purpose of agitating the filter 143 in order to provideadditional dust removing facilities, a vibrating mechanism 173 ismounted upon one wall of the housing 140 as best shown in Figs. 7 and 9.This mechanism comprises a conventional vibrating motor 174 for recip'rocating shaft 174a in order to vibrate a cleaning element 175 inengagement with the outer surface of the filter 143. To provide meansfor removing the dust loosened by the vibrating mechanism 173 in orderto clean the filter 143, a small stream of relatively clean air underpressure is directed from the pressure chamber 169 through a smallopening 141a between plates 141a and 14lb. It will be recalled from theforegoing description that the chamber 169 is open to the pressure sideof the fan 146 so that the air therein is at higher pressure than thatin the inlet chamber 142. The air ejected through the opening flows inthe direction of the arrow pointed lines 168 in Figs. 7 and 9 and passesthrough the filter 143 in a direction opposite to the flow of air intothe,

suction chamber 144. As a consequence, the dust particles are removedfrom the filter and are deposited within the drawer 172.

From the foregoing explanation it will be apparent that u p I I theoperation of the apparatus shownin Figs. 7 and 8 is bracket 158acarrying an idler roller 159 in engagement 7 initiated byenergizingmotors 15 0 and 151 in order to .9 rotate the fan 146 atrelatively high speed and to move the filter 143 over the plates 141aand 141b 'at' relatively low speed. Rotation of fan 146 produces airunder pressure. within the chamber 169 for passage from outlet 171,through duct 29, to manifold 30, through ducts '34, to compartment 10aand through the slot 10d to impinge upon the traveling sheet 15 ofpaper. Dust laden air created bythe air under pressure is returned tothe inlet 139 through duct 31 in the manner previously described andflows into the inlet chamber 142. A small portion of the dust in the airfalls directly into the drawer 172 by the action of gravity. The dusteliminated from the filter 143 by the flow of incoming air thereacrossis also deposited within the drawer. The air in the inlet chamher 142flows through the filter 143 in order to remove the dust, thereby topass relatively clean air to the suction chamber 144 for recirculationby the fan 146. The filter 143 is continuously agitated by vibratingmechani'sm 173 and is also continuously subjected to the clean airstream passing through opening 141:: in order to provide for theeffective elimination of practically all of the dust particles collectedon the filter. Thus, the apparatus shown in Figs. 7 and 8, like thatshown in Figs. and 6 previously described, cooperates with the cleaninghead 10 and its associated elements to provide a continuously operatedclosed cleaning system wherein circulated air is employed to remove dustfrom an area to be cleaned and is also employed to clean the filteringequipment.

While the particular embodiments of the invention have been shown, itwill be understood, of course, that theinvention is not limited theretosince many modifications may be made and it is therefore contemplated bythe appended claims to cover any such modifications .as fall within thetrue spirit and scope of the invention.

What is claimed as new and desired to be secured by Letters :Patent ofthe United States is:

1. A combined pressure-suction type cleaning device comprising a housingof box-like construction having two side walls, first and second endwalls and top and bottom walls, an inlet in said first end wall fordelivering dustlade-n air to the interior of the housing, a motorsupport secured to one of the side walls and extending into the housing,a motor mounted upon said support and having ashaft portion extendingthrough an opening in said one side wall, a second motor mounted on saidsupport, a rotary filter drum encircling both of said motors and saidsupport and dividing the interior of said housing into a pair ofchambers, one of said chambers being an inlet chamber communicating withthe inlet and located between the outer surface of the drum and thewalls of the housing and the other of said chambers being a suctionchamber located within the drum, means on said support journalling saiddrum for rotation within said housing, gear means connecting said secondmotor to drive said drum, fan blades mounted on said shaft portion ofsaid first motor adjacent said opening, a closure secured to saidhousing and enclosing said fan to define a pressure chambercommunicating with the suction chamber through said fan blades and saidopening, whereby rotation of said fan blades by said first motor createssuction within the suction chamber in order to draw dustladen air fromthe inlet chamber through the filter drum and also creates pressurewithin the pressure chamber, an outlet from the pressure chamber fordelivering pressurized air, baffle means for directing the air from theinlet to pass tangentially over said drum between the drum periphery andthe top wall, said journalling means being effective to support saiddrum in a position wherein it is spaced from but close to the top walland said second end wall in order to define regions where the air fromthe inlet speeds up as it passes tangentially over the drum surface inorder to remove dust collected on the drum and force the removed dust tothe bottom of the housing, and baflle means adjacent said inlet fordirecting the gamers,

inlet air through the. region between the top wall andtl e drum. i i

2 The apparatus defined by claim 1 wherein removable collecting meansare provided adjacent the bottomof said housing for collecting dustparticles removed from the filter drum.

3. A combined pressure-suction type cleaning device comprising a housingof box-like construction having two side walls, first and second endwalls and top and bottom walls, an inlet in the first end wall fordelivering dust-laden air to the interior of the housing, a motorsupport secured to one of the side walls within said housing, a motormounted upon said support and having a shaft portion extending throughan opening in said one, side wall, a second motor mounted on saidsupport, 'a rotary filter drum encircling both of said motors and saidsupport and dividing the interior of said housing into a pair ofchambers, one of said chambers being an inlet" chamber communicatingwith the inlet and located between the outer surface of the drum and thewalls of: the housing and the other of said chambers being a suctionchamber located within the drum, means on said support journalling saiddrum for rotation within said housing, means connecting said secondmotor to drive said drum, fan blades mounted on said shaft portion ofsaid first motor adjacent said opening, a closure secured to saidhousing and enclosing said fan to "define a preS- sure chambercommunicating with the suction chamber through said fan blades and saidopening, whereby rotation of said fan blades by said first motor createssuction within the suction chamber in order to draw dust-laden air fromthe inlet chamber through the filter drum and also creates pressurewithin the pressure chamber, an outlet from the pressure chamber fordelivering pres surized air, means for causing the air from the drum topass over the drum surface between the drum periphery and the top wall,said journalling means being effective to support said drum in aposition wherein it is spaced from but close to the top wall of thehousing in order to provide a region where the air from the inlet speedsup as it passes over the drum surface in order to remove dust collectedthereon and force it to the bottom of the housing. I

4. A combined pressure-suction type cleaning device comprising a housingof box-like construction having 'two side walls, two end walls and topand bottom walls, an inlet for delivering dust-laden air to the interiorof the housing, a motor support secured to one of the walls andextending into said housing, a motor mounted upon said support andhaving a shaft portion extending through an opening in said one wall, asecond motor mounted on said support, a rotary filter drum encirclingboth of said motors and said support and dividing the interior of saidhousing into a pair of chambers, one of said chambers being an inletchamber communicating with the inlet and located between the outersurface of the drum and the walls of the housing and the other of saidchambers being a suction chamber located within the drum, means on saidsupport journalling said drum for rotation within said housing, meansconnecting said second motor to drive said drum, fan blades mounted onsaid shaft portion of said first motor adjacent said opening, a closuresec-cred to said housing and enclosing said fan to define a pressurechamber communicating with the suction chamber through said fan bladesand said opening, whereby rotation of said fan blades by said firstmotor creates suction within the suction chamber in order to drawdust-laden air from the inlet chamber through the filter drum and alsocreates pressure within the pressure chamber, an outlet from thepressure chamber for delivering pressurized air, said journalling meansbeing effective to support said drum in a position wherein it is spacedfrom but close to at least one of the walls of the housing in order toprovide a region where the air from the inlet speeds up as it passestangentially over the drum surface in order to remove dust collectedthereon and force it to the botto nrof the housing,,and means forcausing air from the inlet to pass tangentially over the drum surfacebetween the drum and said one wall of the housing. H

5. The apparatus defined by claim 4 wherein there is provided bafiiemeans carried by the housing adjacent said inlet for directingdust-laden air into said region and tangentially across the drumperiphery.

6. A combined pressure-suction type cleaning device comprising a housingof box-like construction having side 1 walls and top and bottom walls,an inlet for delivering dust-laden air to the interior of the housing,support structure secured to one of the side walls and extending intosaid housing, a rotary filter drum supported by said support structureand dividing the interior of said housing into a pair of chambers, oneof said chambers being an inlet chamber communicating with the inlet andlocated between the outer surface of the drum and the walls of, thehousing and the other of said chambers being a suction chamber locatedWithin the drum, means on said support journalling said drum forrotation within said housing, means for rotating said drum, a fan bladesupported by said support structure and communicating with said suctionchamber, means defining a pressure chamber communicating with thesuction chamber through said fan, whereby rotation of said fan createssuction Within the suction chamber in order to draw dust-laden air fromthe inlet chamber through the filter drum and also creates pressurewithin the pressure chamber, an outlet from the pressure chamber j fordelivering pressurized air, said journalling means being effectivetosupport said drum in a position wherein it is spaced from but close tothe top wall and at least one of the side walls of the housing in orderto provide regions where the air from the inlet speeds up as it passestangentially over the drum surface in order to remove dust collectedthereon and force it to the bottom of the housing, and-bafile meansadjacent said inlet for directing the inlet air to pass tan gentiallyover the drum surface through the region between the top wall and thedrum.

7. A combined pressure-suction type cleaning device comprising a housingof box-like construction having side walls and top and bottom walls, aninlet for delivering dust-laden air to the interior of the housing,support structure secured to one of the walls and extending into a a, .112 said housing, a rotary filter drum supported by said supportstructure and dividing the interior of said housing into a pair ofchambers, one of said chambers being an inlet chamber communicatingwiththe inlet and located between the outer surface of the drum and thewalls of the housing and the other of said chambers being a suctionchamberlocated within the drum, means on said support journalling saiddrum for rotation within said housing, means for rotating said drum, afan supported by said support structure and communicating with thesuction chamber, means defining a pressure chamber around said fan sothat rotation of said fan creates suction within the suction chamber inorder to draw dustladen air from the inlet chamber through the filterdrum and also creates pressure within the pressure chamber, an outletfrom the pressure chamber for delivering pressurized air, saidjournalling means being efiective to support said drum in a positionwherein it is spaced from but close to at least one of the walls of thehousing in order to provide a region where the air from the inlet speedsup as it passes tangentially over the drum surface in order to removedust collected thereon and force it to the bottom of the housing, andmeans for causing air from the inlet to pass tangentially over the drumsurface and through the space between the drum and said one wall of thehousing.

References Cited in the file of this patent UNITED STATES PATENIS

